Free men and women are, of course, capable of violence, even murder, but unless it is proven that they are embarking on these, unless the burden of proof is fully met, they must be left free. The job of protecting the citizenry must be carried out without violating their rights. That is the spirit behind constitutional government, especially the American Bill of Rights.
If and when one signs up to work in the security professions, one must adhere to strict standards and do one’s job without violating them. One must cope with the limits and not run rampant unrestrained. (It is a bit like medical research and experimentation–it is all very important but doesn’t justify ignoring the basic rights of patients or subjects!)
That our government officials fail to grasp all this is truly a disaster. When they refuse to act within the limits posed by our individual rights, they are a far greater danger than terrorism! Indeed, they become like terrorists, making use of arbitrary means to reach their goals! Nothing excuses it!
The oath of office of all security professionals includes a commitment to act without doing violence of the rights of the citizenry, including to their right to privacy and due process.